Photographic shutter



(No Model.)

G. F. GREEN.

PHOTOGRAPHIO SHUTTER.

Patented July 29, 1890.

UNITED STATES PATENT OFFICE.

GEORGE F. GREEN, OF KALAMAZOO, MICHIGAN.

PHOTOGRAPHIC SH UTTER.

SPECIFICATION forming part of Letters Patent No. 432,999, dated July 29, 1890.

Serial No. 317,269. (No model.)

To all whom it may concern.-

Be it known that I, GEORGE F. GREEN, of

Kalamazoo, in the county of Kalamazoo, and the State of Michigan, have invented new and useful Improvements in Camera or Photographic Shutters; and I do hereby declare that the following is a full and accurate description of the same, reference being had to the accompanying drawings, wherein- Figure 1. is a perspective view of my shutter. Fig. 2 is an elevation of the shutters separated. Fig. 3 is an elevation of the same together. Fig. at is a section in line with the axis of the aperture.

This shutter belongs to that class which has folding wings opening and closing by movements in opposite directions in parallel planes transverse to the axis of the lens.

The objects of my invention are, first, to cause each leaf of the shutter to openand close again by two movements in opposite directions impelled by a single rectilinear motion of the actuating-force; second, to open and close'the shutter, as above, by motion on a pivot at one side of the lens-aperture to produce a larger and longer exposure of one part of the picture'than another; third, in the elastic cushions to receive the wings when they open to prevent noise and jar; fourth, in the lock, whereby the wings are prevented from moving, except when desired, and, fifth, in a fibrous lining covering the inner face of the shuttercase to deaden sound and prevent leakage of light.

That others may fully understand my i11- vention, I will particularly describe it.

A is the shutter case or frame, and Bis the ordinary pneumatic engine for operating the shutter-wings. This engine is operated by pneumatic pressure produced usually by compressing an elastic bulb, and thereby forcing air under pressure into the engine.

0 andD are the wings of the shutter. They may be both mounted on the same pivot-pin 6. Each of said wings includes rather more than one-half a circular disk, so that when they are closed together their adjoining edges will overlap each other and exclude light. The pivot-pin e being below the aperture, the shutters move faster at the extremities of the wings over the far margin of said aperture than at the margin nearer said pivot-pin, and therefore light will be admitted more abundantly on the far side than on the nearerside; and in mounting the shutter it is so adjusted that the flood of light, or larger exposure, comes from foreground, and the lesser quantity from the sky. The object and effect of this are to equalize the illumination of the sensitive plate. I am aware that attempts to accomplish this end have been made heretofore by openings of various shapes in sliding shutters; but such shutters are required to slide horizontally, and necessarily commence the exposure at one margin and close it at the other, and therefore the beam of light moves across the plate, instead of beginning at a certain point, expanding therefrom, and quenching at the point of beginning, which is universally believed to be the preferable mode.

The shutter-wings O D open by moving away from each other and close by moving toward each other, and this movement and counter-movement are produced by one continuous rectilinear movement of the engine. The wing G is provided with a single curved slot f, having the concave side toward the pivot 6; but it is so located as to said center that nearly the whole length of said slot extends toward that side of said pivot which is toward the engine B. The pin g, attached to the piston of the engine B, projects through said slot and normally rests in the extremity thereof, and is in diameter suflicient to fill the width of said slot. The pin 9 moves in a straight line, which is a chord of the curve of said slot, and therefore in moving along said line the edge of the slot will be engaged and the wing caused to move in a direction opposite to the motion of the pin. This is because the pin acts as a cam pressing downward or laterally on the wing at points lateral as to the pivot, and said downward pressure continues until the pin reaches apoint above and nearest said pivot. After passing said nearest-point the action of the pin will be an upward or outward lateral pressure, and the movement of the wing will therefore be reversedand move in the same direction as the pin g. As a matter of convenience, the slot terminates at the point reached by the pin as it passes the pivot 6, so that the reverse movement of the wing will bepartly due to'a direct thrust of the pin at the end of said slot. The action, therefore, is partly that of a cam and partly that of a crank. IVhen the pin g and the wing C come to rest, the pin is in the inner end of the slot, which 011 the retrograde movement of the pin presents itself in the same relation to the pin, and therefore the wing is caused to repeat its movements, so that in whichever direction the pin moves the shutter has imparted to it the two mot-ions above described.

The shutter D, having to be moved by the same pin and coincidentally with shutter 0, but in opposite directions therefrom, requires a different form of slot, because its first motion is in the same direction with the motion of the pin. The shutter D is therefore provided with a slot h, the outer extremity of which is nearly above the pivot-pin when the shutter is closed. The outer half of said slot is curved with the concavity toward the pivot, but the inner half turns sharply upward. The pin 9 rests in the inner extremity of said slot when the shutters are closed, and at the angle or midway when the shutter is fully open. Under these circumstances the advance of the pin 9 will act upon the upward portionl of said slot and push the shutter open, but cannot act upon any portion to push it shut again while said pin continues to advance. I therefore attach to the piston a second pin 70, which, moving in a line parallel with the movement of the pin g, but on the opposite side of the pivot 6, presents itself in an opposite relation to the wing D. I therefore place in the lower margin of the wing D a shoulder at, located so that when the pin 9 has advanced far enough to open said shutter the pin will engage said shoulder and close the shutter again. Therefore in causing the movements of the shutter D the action of the engine is partly that of a cam and partly that of a crank.

Because the wings of the shutter open and close again by reciprocation and move with considerable rapidity, it is necessary to avoid jar and sound at the completion of the first or opening movement, and I therefore attach to the shutters pieces of india-rubber or other suitable material 19. For this purpose indiarubber is better than any other material, because of its great elasticity and power to absorb and neutralize concussion. No vibra tion from a blow delivered upon an indiarubber cushion will be transmitted to the parts beyond. The pieces 19 of india-rubber pass through the shutter-case from side to side, and therefore extend across the space in which the shutter-wings move and admit of no space between said india'rubber and the shutter-case, into which the wing may drive and be wedged fast.

When a time exposure is desired, an obstruction may be placed to arrest the piston at the middle of its movement. This obstrud tion may be arranged in various ways. I have employed a pivoted stop 8 as a convenient and efficient method. Its lever end may project through the front of the camera, so that the stop may be operated from without. It is also desirable to provide some method of locking the Wings to prevent them from moving when not desired. This is useful when the carrier is being moved from place to place, and in the class of small cameras which use continuous sensitive films without slides, depending upon the exposing shutter for the exclusion of light; and I therefore provide a positive locking-pin T, arranged to pass through the shutter-blades. It is manifest that many other forms of lock taking hold of both wings and holding them may be employed, and I therefore do not desire to be limited to the particular form shown.

My shutter may be placed in front of, between, or behind the lenses, as desired, and the form of the case or frame may be modified accordingly. The form shown in the drawings is intended to be placed behind the lens within the camera. WVhen placed within the camera, the mechanism is concealed and protected from injury, and light is more effectually excluded; but in the form shown in the drawings it may be attached to the front of the lens by the addition of a proper collar or ring adapted to slip over the front end of the lens-tube. WVhen placed within the camera, it is desirable to produce a close fit without trouble and without special workmanship, and it is also desirable to deaden all sounds arising from the action of the moving parts. I therefore cover the back of the shutter-frame with a layer or coating of fibrous material U, which renders the shutter-frame self-adapting to the front of the camera and capable of preventing leakage of light and the transmission of sound.

Having described my invention, I claim- 1. In a photographic shutter, two wings pivoted at one side of the aperture and the overlapping edges fashioned to separate on a line through the axis of the lens, and thereafter to separate more rapidly at one side of said aperture than at the other side, combined with an engine adapted to open and close the wings of said shutter by movements in opposite directions, as set forth, for the purpose of flooding the foreground with light, as set forth.

2. In a photographic shutter, two wings pivoted at one side of the aperture and respectively provided with slots f h, substantially as shown, combined with a pneumatic actu ating-engine acting in'said slots to cause said shutters to open and close by a single motion of the engine, as set forth.

3. In a photographic shutter, two Wings 0 and D, pivoted at e and respectively provided with slots f h, and the shoulder 02 on wing D, substantially as shown, combined with the engine B, provided with pins 9 and 70, moving in parallel straight lines to open and close the shutter by a single movement of said engine.

IIO

closes said wings on both sides thereof, and I0 elastic buffers 1.), extending across the shutterspace and into the plates of the case on either side of the same.

GEORGE F. GREEN.

Witnesses:

H. GREEN, GEo. M. GOLDEN. 

